| Popis: |
Reactions of M(IV) halides with the six-membered triazacyclohexane (MeNCH 2 ) 3 provide the ionic salts [MeN(CH 2 NMe) 2 CH] 2 [MX 6 ]·MeCN where M=Te, X=Cl ( I ); M=Te, X=Br ( II ) and M=Sn, X=Br ( III ), as confirmed by spectroscopic and single crystal X-ray diffraction studies. The individual [MeN(CH 2 NMe) 2 CH] + cations contain a planar (Me)NCHN(Me) segment reminiscent of amidinium formation (mean): NC, 1.31(1) A; NCN, 123.3(1)°. A plausible reaction pathway involving an incipient release of a hydride ion from a CH 2 unit of the bound ligand and a subsequent attack (nucleophilic) at the β-carbon of a coordinated acetonitrile (solvent) molecule is discussed. Supporting evidence for activation of the acetonitrile via a nucleophilic attack comes from the reaction system GeBr 4 / i C 3 H 7 NHCOCH 2 CONH i C 3 H 7 /CH 3 CN, which provides the cationic organohydrobromide salt [CH 3 C(CH(CONH i C 3 H 7 ) 2 ) 2 NH 3 ]Br ( IV ). The structure of IV reveals two malonamide fragments attached to the acetonitrile residue. The reaction of TeBr 4 and [9]aneS 3 provides orange crystals of a product identified spectroscopically and by X-ray diffraction studies as the bicyclic sulphonium salt [C 6 H 11 S 3 ] 2 [TeBr 6 ]·MeCN ( V ). A plausible reaction pathway, namely molecular oxidation with CH activation resulting in hydride ion expulsion, is suggested. The structure of the bicyclic cation reveals a five-membered ring and a six-membered ring fused along a common SC linkage, 1.825(6) A. The peripheral SC bond distances lie in the range 1.800(5)–1.822(5) A. The reaction of TeCl 4 and Me 3 [9]aneN 3 in toluene gives orange crystals of the doubly-protonated ligand salt [(Me 3 [9]aneN 3 )H 2 ][TeCl 6 ]·C 6 H 5 CH 3 ( VI ). An extensive pattern of intra- and inter-molecular hydrogen bonding is observed. |
Full Text from ScienceDirect